CONDENSED CONSOLIDATED STATEMENTS OF EARNINGS (LOSS) - (Unaudited) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 29, 2014	Jun. 30, 2013	Jun. 29, 2014	Jun. 30, 2013
Income Statement [Abstract]
Net sales	$ 102,980	$ 105,381	$ 203,686	$ 203,443
Costs and expenses:
Cost of goods sold	69,157	72,981	139,248	144,257
Selling, general and administrative expenses	15,813	17,157	29,454	34,833
Research and development expenses	5,332	5,771	10,958	12,023
Restructuring and impairment charges	2,733	7,029	3,236	7,206
Operating earnings	9,945	2,443	20,790	5,124
Other (expense)/income:
Interest expense	(582)	(1,058)	(1,195)	(1,964)
Interest income	688	446	1,252	859
Other	(409)	398	(2,180)	(109)
Total other expense	(303)	(214)	(2,123)	(1,214)
Earnings from continuing operations before taxes	9,642	2,229	18,667	3,910
Income tax expense	3,281	12,482	7,226	11,176
Earnings (loss) from continuing operations	6,361	(10,253)	11,441	(7,266)
Discontinued operations
Loss from discontinued operations, net of tax	0	(1,082)	0	(501)
Net earnings (loss)	$ 6,361	$ (11,335)	$ 11,441	$ (7,767)
Basic
Continuing operations	$ 0.19	$ (0.31)	$ 0.34	$ (0.22)
Discontinued operations	$ 0.00	$ (0.03)	$ 0.00	$ (0.01)
Basic net earnings per share	$ 0.19	$ (0.34)	$ 0.34	$ (0.23)
Diluted
Continuing operations	$ 0.19	$ (0.31)	$ 0.33	$ (0.22)
Discontinued operations	$ 0.00	$ (0.03)	$ 0.00	$ (0.01)
Diluted net earnings per share	$ 0.19	$ (0.34)	$ 0.33	$ (0.23)
Cash dividends declared per share	$ 0.040	$ 0.035	$ 0.080	$ 0.070
Average common shares outstanding:
Basic	33,741	33,589	33,725	33,556
Diluted	34,208	33,589	34,244	33,556